The use of herbs is a time-honored approach to strengthening the body and treating disease. However, herbs can trigger side effects, and interact with other herbs, supplements, or medications. For these reasons, you should take herbs under the supervision of a health care provider qualified in the field of botanical medicine.
Garlic is listed as Generally Recognized as Safe (GRAS) by the U.S. Food and Drug Administration (FDA).
Side effects include upset stomach, bloating, bad breath, body odor, and a stinging sensation on the skin from handling too much fresh or dried garlic. Handling garlic may also cause skin lesions. Other, more rare side effects that have been reported by those taking garlic supplements include headache, fatigue, loss of appetite, muscle aches, dizziness described as vertigo, and allergies such as an asthmatic reaction or skin rash.
Garlic acts like a blood thinner. Too much garlic can increase your risk for bleeding during or after surgery. It may also interact with blood-thinning medications.
People with ulcers or thyroid problems should ask their doctors before taking garlic.
Garlic may interact with a number of medications. Some of these medications are listed below. To be safe, if you take any prescription medicines, ask your doctor before taking garlic supplements.
Isoniazid (Nydrazid): This medication is used to treat tuberculosis. Garlic may interfere with the absorption of isoniazid, meaning the drug might not work as well.
Birth control pills: Garlic may make birth control pills less effective.
Cyclosporine: Garlic may interact with cyclosporine, a medication taken after organ transplant, and make it less effective.
Blood-thinning medications: Garlic may make the actions of blood-thinning medications including warfarin (Coumadin), clopidogrel (Plavix), and aspirin stronger, increasing the risk of bleeding.
Medications for HIV/AIDS: Garlic may lower blood levels of protease inhibitors, medications used to treat people with HIV. Protease inhibitors include:
- Amprenavir (Agenerase)
- Fosamprenavir (Lexiva)
- Indinavir (Crixivan)
- Nelfinavir (Viracept)
- Ritonavir (Norvir)
- Saquinavir (Fortovase)
Nonsteroidal anti-inflammatory drugs (NSAIDs): Both NSAIDs and garlic may increase the risk of bleeding. NSAIDs include ibuprofen (Advil, Motrin) and naproxen (Aleve), as well as prescription medications.
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